In a configuration with the back-end connections crossed, the FC connections from the same storage array controller go to both fabric switches (redundant).

This connection scheme makes better use of both switch ports and storage array ports than if the back-end connections are not crossed, which reduces the impact of a switch or storage array controller failure.

For storage arrays with only two controllers, a crossed eight-port LUN group configuration is preferred over an eight-port array LUN group configuration that is not crossed.

You can only cross the eight-port array LUN group when there are dedicated paths from each node (one FC initiator-to-one-target-port zoning per path).

In this illustration of crossed back-end connections, note how the ONTAP systems are attached to the switches and to the storage array. Vs1 uses switch 1 when attaching to the storage array Controller 1 port 1A and Controller 2 port 2C, and uses switch 2 when attaching to storage array Controller 2 ports 2A and Controller 1 port 1C.

The following table summarizes the zoning for an eight-port array LUN group with crossed back-end connections. Single-initiator zoning is the recommended zoning strategy.

In a configuration in which the back-end connections are not crossed, the FC connections from the same storage array controller go to only one fabric switch.

The following illustration shows pathing in a configuration with an eight-port array LUN group in which the back-end connections are not crossed:

The following table summarizes the zoning for an eight-port array LUN group when the back-end connections are not crossed. Single-initiator zoning is the recommended zoning strategy.

When setting up a configuration with an eight-port array LUN group, you cannot exceed the number of array LUNs that ONTAP supports per FC initiator port.